Effectiveness Of Nonlinear Energy Sink Research Articles

Torsional vibration attenuation of a closed-loop engine crankshaft system via the tuned mass damper and nonlinear energy sink under multiple operating conditions

In recent years, nonlinear energy sink (NES), as a nonlinear dynamic vibration absorber (NDVA), has been widely studied due to its high robustness and broadband vibration attenuation effectiveness, compared with the traditional linear dynamic vibration absorber (LDVA). In the area of crankshaft torsional vibration reduction, the external excitation of a closed-loop crankshaft model changes with the variation of speed, which puts forward higher requirements for wide-band torsional vibration attenuation. This study attempts to explore the feasibility of NES replacing the traditional linear tuned mass damper (TMD) for engine crankshafts in possible practical engineering application by studying a four-cylinders diesel engine crankshaft. Firstly, a multi-inertias nonlinear closed-loop self-excited coupled oscillation model (M-NCSCO) of crankshaft is established, and the correctness of the model is verified through comparison with those from experiments. Based on this, the crankshaft is coupled with optimal TMD (O-TMD), general NES (G-NES), and optimal NES (O-NES), respectively. An improved Newmark–β method is proposed to solve the nonlinear dynamic model numerically. The effects of NES and TMD on the vibration attenuation behavior of the crankshaft are studied under different engine operating conditions (including power, injection timing, single cylinder flameout, and load). The results show that the vibration attenuation efficiency and robustness of G-NES are 7.90% and 3.47% higher than that of O-TMD when considering the above four typical working conditions comprehensively. After further optimization of G-NES, the vibration reduction efficiency of O-NES is improved by 3.1% compared with G-NES.

The vibration mitigation of jacket offshore platform based on inerter nonlinear energy sink

The application of the traditional passive vibration control system is limited by the demand for large mass. To ameliorate this situation, the inerter nonlinear energy sink (NES) is introduced and applied, as the substitute for the traditional passive vibration control system, to vibration mitigation of jacket offshore platform under random wave loading, since it has the clear advantage of obtaining apparent vibration control effect through low amounts of added mass. For one thing, the equation of jacket offshore platform including inerter NES is developed considering wave loads. For another, the optimal parameters of inerter NES are obtained through Particle Swarm Optimization (PSO) using numerical simulations. Both analytical and numerical results strongly support that the inerter NES contributes greatly to vibration suppression, compared with traditionally tuned mass dampers (TMD). To explore more practical benefits, further comparison between the vibration mitigation of inerter NES and the optimal TMD system, considering different masses and stiffness, is made right after, which verifies the effectiveness and robustness of inerter NES. Based on the above study and results, it proves valid to conclude that the inerter NES system allows practical application of vibration mitigation for marine structures.

Suppress the vibration of tool system in milling process

A nonlinear energy sink (NES) is used to suppress the vibration of the tool system in milling operations. The corresponding theoretical analysis is done on the nonlinear vibration absorption characteristics of NES. First, the dynamic model of the milling tool system and the milling force are analyzed. The dynamic model and equation of the tool-NES system are then deduced. The approximate analytical solution is solved by the harmonic balance method, and the correctness of the analytical solution is verified by the numerical solution. The numerical simulation reveals the suppression effect of NES on the transient vibration and steady vibration of the tool system.

The effects of nonlinear energy sink and piezoelectric energy harvester on aeroelastic instability of an airfoil

The potential of absorbing and harvesting energy from a two-degree-of-freedom airfoil using an attachment of a nonlinear energy sink and a piezoelectric energy harvester is investigated. The equations of motion of the airfoil coupled with the attachment are solved using the harmonic balance method. Solutions obtained by this method are compared to the numerical ones of the pseudo-arclength continuation method. The effects of parameters of the integrated nonlinear energy sink-piezoelectric attachment, namely, the attachment location, nonlinear energy sink mass, nonlinear energy sink damping, and nonlinear energy sink stiffness on the dynamical behavior of the airfoil system are studied for both subcritical and supercritical Hopf bifurcation cases. Analyses demonstrate that absorbing vibration and harvesting energy are profoundly affected by the nonlinear energy sink parameters and the location of the attachment.

Influence of geometric nonlinearity of rectangular plate on vibration reduction performance of nonlinear energy sink

The differences between the vibration reduction of a NES (nonlinear energy sink) on a nonlinear plate and a linear plate are compared, and the effect of NES on the nonlinear plate is mainly analyzed. The nonlinear equations of the plates connected to NES are derived and subsequently solved by the complexification-averaging method and least square method. The amplitude of the first mode of the nonlinear plate is several times higher than that of the linear plate under large excitation when the two plates are attached to identical NES. The amplitudes of the second mode of the two NES equipped plate are similar. However, super-harmonic resonance responses of the two systems are significantly different. The evolution of the higher branch responses in super-harmonic resonance frequency band of the second mode is analyzed, and found to be significantly different with respect to that in the primary resonance frequency band of the first mode.

A multifunctional lattice sandwich structure with energy harvesting and nonlinear vibration control

A new multifunctional lattice sandwich structure consisting of a lattice sandwich beam, a nonlinear energy sink (NES) and a giant magnetostrictive material (GMM) is proposed in this research. This structure exhibits excellent self-vibration suppression and aeroelastic energy harvesting performance. The dynamic equations of the whole structure are established using Hamilton principle and Newton’s second law, and the Runge-Kutta algorithm is used to obtain the amplitude response of the beam coupled with NES and without NES, which can indicate the vibration control effect of NES. Moreover, the energy harvest effect of the structure with GMM is also analyzed through numerical simulation. And a comparative analysis of relevant parameters such as NES mass, spring stiffness and damping coefficient is also implemented. The results show that this new multifunctional lattice sandwich structure can achieve the desired effect of vibration suppression and energy harvesting, and proper adjustment of parameters will improve the effect. This study provides a new idea for related research on vibration control and energy harvesting.

Vibration suppression and higher branch responses of beam with parallel nonlinear energy sinks

The effects of nonlinear energy sink (NES) on vibration suppression of a simply supported beam are investigated in this work. The slow flow equations of the system are derived by using complexification–averaging method, and the validity of the derivation is verified. By comparing the vibration absorption of single and parallel NESs of equal mass, it is found that the latter exhibits superior vibration absorption performance. In addition, the parallel NES can eliminate higher branch responses of the system under the harmonic load. Furthermore, it is found that parallel NES can eliminate the higher branches of the system more effectively by tuning nonlinear stiffness and damping. Moreover, the thermal effect on natural frequencies of the simply supported beam is considered, and the influences of the parallel NES’s parameters on the energy dissipation rate under shock load are investigated. The nonlinear responses of the simply supported beam with parallel NES under harmonic load and with the increase of temperature are described.

Activation characteristic of a vibro-impact energy sink and its application to chatter control in turning

The ultimate goal of this paper is to propose a procedure for the optimal design of a Vibro-Impact (VI) Nonlinear Energy Sink (NES) to control the vibration of any possible linear or nonlinear main systems. To this end, the activation characteristic of VI NES at a range of displacement amplitude of a main system is generalized from linear systems to nonlinear systems. It is theoretically proved and experimentally observed that this activation characteristic is almost independent of frequency, which provides direct proof for the effectiveness of VI NES in a broad frequency bandwidth. In terms of vibration control, this feature is very attractive and builds a bridge between linear and nonlinear systems. Then it is applied for the design of VI NES attached to nonlinear systems. In this way, the design of VI NES for a nonlinear system is simplified to the optimal design for a linear system, which is designed to be similar to this target nonlinear system. Because the latter can be analytically calculated, the proposed method is feasible from a quantitative perspective. Finally, this activation characteristic and a proposed design method are applied to control chatter in a turning process, and results prove its feasibility.

Steady state dynamics of a non-linear beam coupled to a non-linear energy sink

A non-linear, simply supported beam under harmonic excitation coupled to a non-linear energy sink (NES) is considered here. The NES has a non-linear stiffness of order three. Steady state dynamic of the beam is investigated by two different theories of Euler–Bernoulli and Timoshenko. Complex averaging method combined with arc-length continuation is used to achieve an approximate solution for the steady state vibrations of the system based on 1:1 resonance condition. In order to design an optimized NES for the purpose of reducing the vibration amplitude of the beam, the effect of NES parameters on the amplitude of the primary system is investigated by varying the parameters, individually. The results demonstrated a significant reduction in the vibration amplitude of the original system. By illustrating the frequency spectrum, other harmonic components are detected and the steady state dynamic of the non-linear primary system is computed including the higher harmonics. Non-linear dynamic studies such as bifurcation analysis and Poincare׳ sections are also applied in order to study the effect of NES on the vibration behavior of the beam, in a more accurate manner. Numerical simulations confirm the accuracy of the approximate solutions. Robustness of the NES against changes in the amplitude of excitation is also investigated. Also the performance of NES is compared with linear vibration absorber.